Washington State spans a wide range of USDA planting (hardiness) zones, reflecting its diverse climate from west to east. The zones range approximately from 4a in colder inland and mountainous areas to 9a in the warmer western coastal regions. Much of eastern Washington falls into zones 6a to 7a, while western Washington, including areas like Seattle and the coast, generally ranges from 7b to 9a
. Key points:
- Western Washington has a milder, Mediterranean climate with zones mostly between 7b and 9a, recently updated to include zone 9a in some areas like Shoreline/North Seattle due to warming trends
- Eastern Washington experiences a drier, more continental climate with colder winters, and zones mostly between 4a and 6a
- The USDA zones are based on average annual minimum winter temperatures and help gardeners select plants that will survive the local winters
In summary, Washington State’s planting zones range from USDA zone 4a in colder inland areas up to zone 9a in the mildest coastal areas, with most of the state falling between zones 6a and 9a depending on location
